An in vivo supporting device or barrier device, such as a stent, is a man-made “tube” or “frame” inserted into a natural passage or conduit in the body to prevent, or counteract, a disease-induced, localized flow constriction or flow outflow like a leak or aneurysm. Supporting stents include vascular supporting stents, non-vascular supporting stents, and aneurysm sealing stents. Vascular supporting stents are designed for applications in the vascular system, such as arteries and veins. Non-vascular supporting stents are used in other body lumens such as biliary, colorectal, esophageal, ureteral and urethral tract, and upper airway. Aneurysm sealing stents are used to close off potentially dangerous aneurysms or pseudo aneurysms throughout the vascular and non-vascular system.
Percutaneous transluminal angioplasty (PTA) has evolved over the past 20 years to become a common therapeutic technique for the treatment of peripheral vascular disease. Self-expanding stents are delivered to a desired site mounted onto a stent delivery catheter and are held in place on the catheter by an outer cover until the stent has reached the deployment site. The outer cover is retracted and the stent expands off the catheter to contact the walls of the lumen, where it is held in place by the chronic outward pressure of the stent against the walls of the lumen.
There are several problems with self-expanding stents currently on the market, including the fact that their design takes into account only their expansion at the site of deployment, without regard to the twisting and bending that the stent must do to navigate blood vessels on the way to the deployment site, which can cause the stent to collapse, resulting in damage to the stent that impairs proper deployment. Additionally, there exists the possibility of the stent foreshortening, displacing or jumping during deployment, causing the stent to be emplaced improperly, requiring removal of the stent and replacement with another.
Therefore, there is an existing need for a self-expanding stent that, irrespective of the insertion site, is capable of enduring the twisting inherent in the delivery process and that evenly expands at the deployment site without foreshortening.